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Revpi 2891/dma one byte support #142

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a7f1c15
Linux 5.10.152-rt75
lclaudio Oct 30, 2022
a1afd9f
Patch DMA Treiber
linosanfilippo-kunbus Feb 7, 2023
e6d77a1
Modify device tree for UART tx DMA
linosanfilippo-kunbus Feb 9, 2023
de9daa8
aenderungen amba treiber
linosanfilippo-kunbus Feb 9, 2023
ef2b588
serial: amba-pl011: Fix data transmission for RS485 when using DMA
linosanfilippo-kunbus Feb 9, 2023
378cf9a
Add tracing
linosanfilippo-kunbus Feb 10, 2023
bccb4aa
Add tracing
linosanfilippo-kunbus Feb 10, 2023
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6 changes: 4 additions & 2 deletions arch/arm/boot/dts/overlays/revpi-flat-s-2022-overlay.dts
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Original file line number Diff line number Diff line change
Expand Up @@ -369,10 +369,12 @@
fragment@8 {
target = <&uart3>;
__overlay__ {
linux,rs485-enabled-at-boot-time;
rs485-rts-active-low;
dmas = <&dma 19>;
dma-names = "tx";
pinctrl-names = "default";
pinctrl-0 = <&rs485_0_pins>;
linux,rs485-enabled-at-boot-time;
rs485-rts-active-low;
rs485-term-gpios = <&expander 14 GPIO_ACTIVE_LOW>;
status = "okay";
};
Expand Down
56 changes: 49 additions & 7 deletions drivers/dma/bcm2835-dma.c
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Original file line number Diff line number Diff line change
Expand Up @@ -592,7 +592,8 @@ static void bcm2835_dma_fill_cb_chain_with_sg(
enum dma_transfer_direction direction,
struct bcm2835_cb_entry *cb,
struct scatterlist *sgl,
unsigned int sg_len)
unsigned int sg_len,
enum dma_slave_buswidth buswidth)
{
size_t len, max_len;
unsigned int i;
Expand All @@ -607,7 +608,7 @@ static void bcm2835_dma_fill_cb_chain_with_sg(
for (addr = sg_dma_address(sgent),
len = sg_dma_len(sgent);
len > 0;
addr += scb->len, len -= scb->len, cb++) {
cb++) {
scb = (struct bcm2711_dma40_scb *)cb->cb;
if (direction == DMA_DEV_TO_MEM) {
scb->dst = lower_32_bits(addr);
Expand All @@ -617,18 +618,46 @@ static void bcm2835_dma_fill_cb_chain_with_sg(
scb->srci = upper_32_bits(addr) | BCM2711_DMA40_INC;
}
scb->len = min(len, max_len);

addr += scb->len;
len -= scb->len;

/* Setup 2D X-Y len*/
scb->len /= buswidth;
scb->len--;
scb->len = BCM2711_DMA40_STRIDE(scb->len);
scb->len |= buswidth;
}
} else {
for (addr = sg_dma_address(sgent),
len = sg_dma_len(sgent);
len > 0;
addr += cb->cb->length, len -= cb->cb->length,
cb++) {
if (direction == DMA_DEV_TO_MEM)
cb->cb->dst = addr;
else
cb->cb->src = addr;
cb->cb->length = min(len, max_len);

addr += cb->cb->length;
len -= cb->cb->length;

if (!c->is_lite_channel) {
/* Setup 2D X-Y len*/
cb->cb->length /= buswidth;
cb->cb->length--;
cb->cb->length <<= 16;
cb->cb->length |= buswidth;
}

trace_printk("DMA: DUMP CB\n");
trace_printk("DMA: CB INFO: 0x%08x\n", cb->cb->info);
trace_printk("DMA: CB src: 0x%08x\n", cb->cb->src);
trace_printk("DMA: CB dst: 0x%08x\n", cb->cb->dst);
trace_printk("DMA: CB length: 0x%08x\n", cb->cb->length);
trace_printk("DMA: CB stride: 0x%08x\n", cb->cb->stride);
trace_printk("DMA: CB next: 0x%08x\n", cb->cb->next);
trace_printk("DMA: DUMP CB END\n");
}
}
}
Expand Down Expand Up @@ -897,6 +926,7 @@ static struct dma_async_tx_descriptor *bcm2835_dma_prep_slave_sg(
WIDE_SOURCE(c->dreq) | WIDE_DEST(c->dreq);
u32 extra = BCM2835_DMA_INT_EN;
size_t frames;
enum dma_slave_buswidth buswidth;

if (!is_slave_direction(direction)) {
dev_err(chan->device->dev,
Expand All @@ -910,6 +940,7 @@ static struct dma_async_tx_descriptor *bcm2835_dma_prep_slave_sg(
if (direction == DMA_DEV_TO_MEM) {
if (c->cfg.src_addr_width != DMA_SLAVE_BUSWIDTH_4_BYTES)
return NULL;
buswidth = c->cfg.src_addr_width;
src = c->cfg.src_addr;
/*
* One would think it ought to be possible to get the physical
Expand All @@ -921,8 +952,13 @@ static struct dma_async_tx_descriptor *bcm2835_dma_prep_slave_sg(
src |= 0x400000000ull;
info |= BCM2835_DMA_S_DREQ | BCM2835_DMA_D_INC;
} else {
if (c->cfg.dst_addr_width != DMA_SLAVE_BUSWIDTH_4_BYTES)
return NULL;
if (c->cfg.dst_addr_width != DMA_SLAVE_BUSWIDTH_4_BYTES) {
if (c->is_lite_channel)
return NULL;
if (c->cfg.dst_addr_width != DMA_SLAVE_BUSWIDTH_1_BYTE)
return NULL;
}
buswidth = c->cfg.dst_addr_width;
dst = c->cfg.dst_addr;
if (c->is_40bit_channel)
dst |= 0x400000000ull;
Expand All @@ -932,6 +968,10 @@ static struct dma_async_tx_descriptor *bcm2835_dma_prep_slave_sg(
/* count frames in sg list */
frames = bcm2835_dma_count_frames_for_sg(c, sgl, sg_len);

/* Set 2D mode for all but lite channels */
if (!c->is_lite_channel)
info |= BCM2835_DMA_TDMODE;

/* allocate the CB chain */
d = bcm2835_dma_create_cb_chain(c, direction, false,
info, extra,
Expand All @@ -942,7 +982,7 @@ static struct dma_async_tx_descriptor *bcm2835_dma_prep_slave_sg(

/* fill in frames with scatterlist pointers */
bcm2835_dma_fill_cb_chain_with_sg(c, direction, d->cb_list,
sgl, sg_len);
sgl, sg_len, buswidth);

return vchan_tx_prep(&c->vc, &d->vd, flags);
}
Expand Down Expand Up @@ -1261,7 +1301,9 @@ static int bcm2835_dma_probe(struct platform_device *pdev)
od->ddev.device_terminate_all = bcm2835_dma_terminate_all;
od->ddev.device_synchronize = bcm2835_dma_synchronize;
od->ddev.src_addr_widths = BIT(DMA_SLAVE_BUSWIDTH_4_BYTES);
od->ddev.dst_addr_widths = BIT(DMA_SLAVE_BUSWIDTH_4_BYTES);
/* TODO: support further byte widths */
od->ddev.dst_addr_widths = BIT(DMA_SLAVE_BUSWIDTH_1_BYTE) |
BIT(DMA_SLAVE_BUSWIDTH_4_BYTES);
od->ddev.directions = BIT(DMA_DEV_TO_MEM) | BIT(DMA_MEM_TO_DEV) |
BIT(DMA_MEM_TO_MEM);
od->ddev.residue_granularity = DMA_RESIDUE_GRANULARITY_BURST;
Expand Down
75 changes: 63 additions & 12 deletions drivers/tty/serial/amba-pl011.c
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Original file line number Diff line number Diff line change
Expand Up @@ -277,6 +277,9 @@ struct uart_amba_port {
};

static unsigned int pl011_tx_empty(struct uart_port *port);
static void dump_buffer(unsigned char *buff, unsigned int len);
static void pl011_rs485_tx_start(struct uart_amba_port *uap);


static unsigned int pl011_reg_to_offset(const struct uart_amba_port *uap,
unsigned int reg)
Expand Down Expand Up @@ -403,18 +406,25 @@ static void pl011_dma_probe(struct uart_amba_port *uap)
/* DMA is the sole user of the platform data right now */
struct amba_pl011_data *plat = dev_get_platdata(uap->port.dev);
struct device *dev = uap->port.dev;
struct dma_slave_config tx_conf = {
.dst_addr = uap->port.mapbase +
pl011_reg_to_offset(uap, REG_DR),
.dst_addr_width = DMA_SLAVE_BUSWIDTH_1_BYTE,
.direction = DMA_MEM_TO_DEV,
.dst_maxburst = uap->fifosize >> 1,
.device_fc = false,
};
struct dma_slave_config tx_conf;
struct dma_chan *chan;
dma_cap_mask_t mask;

tx_conf.dst_addr = uap->port.mapbase +
pl011_reg_to_offset(uap, REG_DR);
// XXX: translate from phys to bus address. Use dma-ranges property
// for this?
tx_conf.dst_addr -= 0x80000000;

printk(KERN_INFO "DST ADDR IS 0x%08x\n", (u32) tx_conf.dst_addr);

tx_conf.dst_addr_width = DMA_SLAVE_BUSWIDTH_1_BYTE;
tx_conf.direction = DMA_MEM_TO_DEV;
tx_conf.dst_maxburst = uap->fifosize >> 1;
tx_conf.device_fc = false;

uap->dma_probed = true;

chan = dma_request_chan(dev, "tx");
if (IS_ERR(chan)) {
if (PTR_ERR(chan) == -EPROBE_DEFER) {
Expand Down Expand Up @@ -553,6 +563,8 @@ static void pl011_dma_tx_callback(void *data)
unsigned long flags;
u16 dmacr;

trace_printk("DMA TX CALLBACK\n");

spin_lock_irqsave(&uap->port.lock, flags);
if (uap->dmatx.queued)
dma_unmap_sg(dmatx->chan->device->dev, &dmatx->sg, 1,
Expand Down Expand Up @@ -588,6 +600,16 @@ static void pl011_dma_tx_callback(void *data)
spin_unlock_irqrestore(&uap->port.lock, flags);
}

static void dump_buffer(unsigned char *buff, unsigned int len)
{
int i;

for (i = 0; i < len; i++)
trace_printk("0x%02x (%c) ", buff[i], buff[i]);

trace_printk("\n");
}

/*
* Try to refill the TX DMA buffer.
* Locking: called with port lock held and IRQs disabled.
Expand Down Expand Up @@ -627,9 +649,12 @@ static int pl011_dma_tx_refill(struct uart_amba_port *uap)
if (count > PL011_DMA_BUFFER_SIZE)
count = PL011_DMA_BUFFER_SIZE;

if (xmit->tail < xmit->head)
if (xmit->tail < xmit->head) {
memcpy(&dmatx->buf[0], &xmit->buf[xmit->tail], count);
else {
trace_printk("Dumping DMA buffer (1)\n");
dump_buffer(dmatx->buf, count);
trace_printk("Dumping DMA buffer (1) END\n");
} else {
size_t first = UART_XMIT_SIZE - xmit->tail;
size_t second;

Expand All @@ -638,8 +663,17 @@ static int pl011_dma_tx_refill(struct uart_amba_port *uap)
second = count - first;

memcpy(&dmatx->buf[0], &xmit->buf[xmit->tail], first);
if (second)

trace_printk("Dumping DMA buffer (2a)\n");
dump_buffer(dmatx->buf, first);
trace_printk("Dumping DMA buffer (2a) END\n");

if (second) {
memcpy(&dmatx->buf[first], &xmit->buf[0], second);
trace_printk("Dumping DMA buffer (2b)\n");
dump_buffer(&dmatx->buf[first], second);
trace_printk("Dumping DMA buffer (2b) END\n");
}
}

dmatx->sg.length = count;
Expand Down Expand Up @@ -673,6 +707,10 @@ static int pl011_dma_tx_refill(struct uart_amba_port *uap)
/* Fire the DMA transaction */
dma_dev->device_issue_pending(chan);

if ((uap->port.rs485.flags & SER_RS485_ENABLED) &&
!uap->rs485_tx_started)
pl011_rs485_tx_start(uap);

uap->dmacr |= UART011_TXDMAE;
pl011_write(uap->dmacr, uap, REG_DMACR);
uap->dmatx.queued = true;
Expand Down Expand Up @@ -789,6 +827,10 @@ static inline bool pl011_dma_tx_start(struct uart_amba_port *uap)
return false;
}

if ((uap->port.rs485.flags & SER_RS485_ENABLED) &&
!uap->rs485_tx_started)
pl011_rs485_tx_start(uap);

pl011_write(uap->port.x_char, uap, REG_DR);
uap->port.icount.tx++;
uap->port.x_char = 0;
Expand Down Expand Up @@ -1357,8 +1399,11 @@ static void pl011_start_tx(struct uart_port *port)
struct uart_amba_port *uap =
container_of(port, struct uart_amba_port, port);

if (!pl011_dma_tx_start(uap))
if (!pl011_dma_tx_start(uap)) {
trace_printk("Using PIO instead of DMA\n");
pl011_start_tx_pio(uap);
} else
trace_printk("Using DMA !!!\n");
}

static void pl011_stop_rx(struct uart_port *port)
Expand Down Expand Up @@ -1432,6 +1477,7 @@ static bool pl011_tx_char(struct uart_amba_port *uap, unsigned char c,
pl011_read(uap, REG_FR) & UART01x_FR_TXFF)
return false; /* unable to transmit character */

trace_printk("PIO - 0x%02x (%c) ", c, c);
pl011_write(c, uap, REG_DR);
uap->port.icount.tx++;

Expand Down Expand Up @@ -1897,6 +1943,9 @@ static int pl011_startup(struct uart_port *port)
/* Startup DMA */
pl011_dma_startup(uap);

trace_printk("%s TX DMA\n", uap->using_tx_dma ? "USING " : "NOT USING ");
trace_printk("%s RX DMA\n", uap->using_rx_dma ? "USING " : "NOT USING ");

pl011_enable_interrupts(uap);

return 0;
Expand Down Expand Up @@ -2797,7 +2846,9 @@ static int pl011_setup_port(struct device *dev, struct uart_amba_port *uap,

uap->port.dev = dev;
uap->port.mapbase = mmiobase->start;
trace_printk("MAPBASE IS 0x%08x\n", (u32) mmiobase->start);
uap->port.membase = base;
trace_printk("MEMBASE IS 0x%08x\n", (u32) base);
uap->port.fifosize = uap->fifosize;
uap->port.has_sysrq = IS_ENABLED(CONFIG_SERIAL_AMBA_PL011_CONSOLE);
uap->port.flags = UPF_BOOT_AUTOCONF;
Expand Down
2 changes: 1 addition & 1 deletion localversion-rt
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@@ -1 +1 @@
-rt74
-rt75